Electron beam and ultraviolet sources are the primary options for irradiating surface layers. Existing surface curing systems, however, are fixed-size configurations and are not easily modified to accommodate different sized surfaces. Surface curing applications can involve web sizes ranging anywhere from 1 inch to 60 inches in width. However, because of the inherent non-scalability of fixed-size surface curing systems, electron beam treatment has been an impractical and therefore seldom used option.
The growth of electron beam systems has stalled due to resistance in a number of areas which challenge the advancement of the technology. First, there is the high cost of the systems resulting from the need for scalability in order to accommodate various surface dimensions. Second, is the overall size of a typical high energy electron beam system, its so-called footprint, which typically includes a vacuum sub-system, the power supply and transformers. A related concern is the need for protective X-ray shielding in high energy electron beam systems. This results in added material and physical complexity of the system.
Operationally, there is concern over the issue of surface reaction rate of the curable material with atmospheric oxygen. This undesirable interaction of the chemistry with oxygen affects the chain reaction of the surface, resulting in improperly treated surfaces. System up-time is another consideration worth noting. With single-unit electron beam devices, failure of any part of the device makes the entire system inoperable.
Manufacture of single-unit systems tends to drive up the cost of these systems. Precise alignment of the individual components comprising such systems is required and testing of large systems is a time consuming effort, adding significantly to the cost of manufacture.
What is needed is an electron beam system suitable for surface curing applications, which can economically be scaled up to accommodate high-speed, wide-web curing operations. At the same time, such a system should have a low specific cost and is compact to accommodate a wide variety of electron beam applications.